In the first place, several terms used in this description will be defined.
The term “facility” means a building or a structure, including commercial facilities such as convenience stores (hereafter, abbreviated as CVS), public facilities such as schools, tourist facilities such as zoos, and road structures such as interchanges, the building or the structure being represented as a landmark or a denotation of a point on a map. This term “facility” may be used interchangeably with the term “POI” (Point Of Interest).
The term “nearby facility” means a facility that is located in an area off an intended route (i.e., in the periphery), or a facility that does not face the intended route. A facility that is located along the intended route shall be referred to as a “roadside facility.”
The term “facility category” means a class for classifying facilities by their types. For example, facility categories of a commercial facility include CVS, bank, family restaurant, clothing store and the like.
The term “symbol” means an icon that represents a map element, such as a facility, on a map.
A technique is known, which provides a navigation device that switches map views to reduce unnecessary symbols based on the user operation among facility symbols to be superimposed on a map.
Patent Literature 1 discloses such a technique. In a navigation device according to Patent Literature 1, ON/OFF display switching of facility symbols and facility categories to be constantly displayed are registered in advance by the user operation. When a map indicating a route guiding to a desired destination is to be displayed, all the facility symbols having display coordinates within the display area of the map are displayed, if the display switching is set to OFF. In contrast, if the display switching is set to ON, all the facility symbols having display coordinates in a detailed display area set around the current position are displayed within the display area, whereas symbols of the facilities belonging to the categories for which the user has set constant display are displayed in the outside of the area.
In a navigation device according to Patent Literature 2, for example, a button for switching facility symbols is displayed on a map so that the facility symbols are switched between the following three methods every time this button is selected by the user. When the switching button is pressed for the first time, all types of the facility symbols are not displayed. When the switching button is pressed for the next time, only one type of the facility symbols A (e.g. a facility symbol of parking area) is displayed.
When the switching button is pressed again then, only another type of facility symbol B other than the facility symbol A that is already displayed (e.g. a facility symbol of CVS) is displayed. In this regard, it can be preliminarily set for each of the facility categories whether or not the facility symbols are displayed, so that every time the switching button is pressed by the user, facility symbols of the facility categories set preliminarily are displayed successively one by one, for example, in the order of the facility symbols B, C, D, . . . Alternatively, the preliminarily set facility categories can be displayed sequentially one by one, except the facility symbols of the categories which are not located in the display area on the map.